I usually have the chorus set to fairly slow and using fairly low level on it.

Two of my presets have it set to a substantial level, making it simply flange-up into a good 'ol days tape phase-out flange Other softer chorus presets sounds just fine.I don't get it, sounds like something is wrong, but I have extremely little time to go debugging (due to rushing out of my apartment).Any clues? This is on the MP-2 that I'll keep, so I can fix it later (like when having relocated to Mars).

While this behavior otherwise could sound quite sexy for certain things, I have little interest in my metal presets sounding like Hendrix' Gipzy Eyes

I think it's just the nature of the beast. With MP-1 I used to turn the chorus depth up to 100 (full) and rate 0.0 just to add a slight very short delay and fatten the sound. The same setting in the MP-2 is quite different and exhibits flange, the chorus circuits work differently, IIRC MJMP explained it well at the time and why you'd get a comb filtering effect.